'Official' Vectrix lithium conversion

I looked into the costs and specs of an official Vectrix dealer conversion to lithium batteries. Needless to say, it's very expensive. There are two battery specs are on offer.... 30AH and 42AH... both from Gold Peak Batteries, the owners of Vectrix. BMS from the same source. In both cases, the original charger is replaced with a Runke charger. Cost is £3934 or £4977.. a lot of money. But, I notice that the lithium batteries have cooling fans built into the battery casings and a new plenum cover is used. Matt's lithium conversion, and another that I've seen explained on youtube, don't have cooling fans at all. Can anyone tell me why Vectrix feel it is necessary to incorporate fans? Presumably, their lithium batteries are not much different from any other in terms of generating heat? The Vectrix dealer conversion "includes the installation of the batteries and requisite sof...